Induction motor and method of adjusting power factor of the same

Abstract

An induction motor capable of producing an increased torque has a stator for generating a rotating magnetic field, a stator fixed to a shaft, a cylindrical member disposed within an inner space defined by the rotor and rotatably supported by the shaft, and magnets attached to the circumference of the rotor such that the magnets face the rotating magnetic field. The induction motor may be provided with a mechanism for adjusting the effective magnetic force of the magnets. The magnets may be permanent magnets or electromagnets. Also, a synchronizing mechanism may be provided to prevent the cylindrical member from lagging behind the rotor. A linear induction motor includes a straight primary coil assembly and a straight secondary coil assembly. One of the primary coil assembly and the secondary coil assembly is movable relative to the other. Also, a plurality of magnets are disposed in the secondary coil assembly. A disc type induction motor includes a flat circular stator, a disc-shaped rotor, and a flat circular magnet disc on which a plurality of magnets are provided.

What is claimed is: 
     
       1. An induction motor comprising: a stator for generating a rotating magnetic field;   a rotor fixed to a shaft for rotation therewith inside said stator, said rotor including a plurality of spaced apart conductors;   a cylindrical member disposed within an inner space defined in said rotor and rotatably supported by said shaft: magnets attached to the circumference of said cylindrical member such that said magnets face the rotating magnetic field; and   a spacer positioned on said shaft which spacer moves said magnets axially with respect to said stator and said rotor and in the axial direction of said shaft so as to change overlapping areas between poles of said stator and said magnets.     
     
     
       2. An induction motor comprising: a stator for generating a rotating magnetic field;   a rotor fixed to a shaft for rotation therewith inside said stator, said rotor including a plurality of spaced apart conductors which generate a force as a function of said rotating magnetic field and said force having a component which is tangential to the rotational direction of said rotor;   a cylindrical member disposed within an inner space defined in said rotor and rotatably supported by said shaft: and electromagnets and permanent magnets attached to the circumference of said cylindrical member such that said electromagnets face the rotating magnetic field whereby said electromagnets redirect a path of said rotating magnetic field in order to increase said tangential component of said force generated in said spaced apart conductors; and   a spacer positioned on said shaft which spacer moves said electromagnet and said permanent magnets axially with respect to said stator and said rotor and in the axial direction of said shaft so as to change overlapping areas between poles of said stator and said electromagnet and said permanent magnets.     
     
     
       3. An induction motor comprising: a stator for generating a rotating magnetic field;   a rotor fixed to a shaft for rotation therewith inside said stator, said rotor including a plurality of spaced apart conductors which generate a force as a function of said rotating magnetic field and said force having a component which is tangential to the rotational direction of said rotor;   a cylindrical member disposed within an inner space defined in said rotor and rotatably supported by said shaft;   magnets attached to the circumference of said cylindrical member such that said magnets face the rotating magnetic field whereby said magnets redirect a path of said rotating magnetic field in order to increase said tangential component of said force generated in said spaced apart conductors; and   means for synchronizing the movement of said cylindrical member and said rotor including a rachet mechanism for preventing said cylindrical member from lagging behind said rotor.